Elevating devices

ABSTRACT

An elevating device comprises three vertically extending post members arranged in two pairs with a motor-operated parallelogram linkage between each pair. The center post is skewed in shape and the two linkages extend in opposite directions to be movable alongside each other in the lower positions of the device, so that it is extremely compact in the stored position (enabling it to pass through a standard doorway) and yet can extend to very substantial heights. Hydraulic linkage motors are used. Each motor is separately controlled and is provided with safety check valves to provide against sudden lowering of the device.

United States Patent [1 1 Merrick [111 3,807,575 [451 Apr. 30, 1974 ELEVATING DEVICES [75] Inventor: John A. Merrick, Dundas, Ontario,

Canada [73] Assignee: Merrick Hydraulics lnc., Ontario,

Canada [22] Filed: June 13, 1972 [211 Appl. No.: 262,391

[52] US. Cl.

2,500,815 3/1950 Cerci 182/2 3,176,792 4/1965 Olson.... 182/2 3,470,980 10/1969 lrwin 182/2 Primary Examiner-Richard E. Aegerter ABSTRACT An elevating device comprises three vertically extending post members arranged in two pairs with a motoroperated parallelogram linkage between each pair. The center post is skewed in shape and the two linkages extend in opposite directions to be movable alongside each other in the lower positions of the device, so that it is extremely compact in the stored position (enabling it to pass through a standard doorway) and yet can extend to very substantial heights. l-lydraulic linkage motors are used. Each motor is separately controlled and is provided with safety check valves to provide against sudden lowering of the device.

6 Claims, 3 Drawing Figures PATENIEBAPR 30 1914 SHEEI 2 [IF 3 PATENTEDAPR 3019M saw a nr 3 nmv K 3kg Om 2m nNm ELEVATING DEVICES FIELD OF THE INVENTION REVIEW OF THE PRIOR ART There is a need in many plants and operations for a movable elevating device that can safely lift small loads, especiallyone or two men, to heights of say 6 to 30 feet. It must be possible to collapse the device to a stored position in which it can pass easily through a standard plant doorway, which usually measures 36 inches by 80 inches. This restriction does place severe limitations on the structure, to the extent that it has proven difficult to provide devices that will extend more than about 30 feet.

The simpler forms of such devices make use ofa single motor-controlled linkage, and there have been a number of proposals to use two linkages in series" with one another, in order to extend the distance the device will elevate a man or other load. Reference is' made for example to the apparatus shown in U.S. Pat. Nos. 2,674,500 and 3,283,850.

DEFINITION OF THE INVENTION It is an object of the invention to provide a new elevating device.

It is a more specific object to provide a new elevating device employing two elevating linkages in series with one another, and which can assume'an exceptionally compact stored" position for. ease of movement thereof.

In accordance with the present invention there is provided an elevating device movable by a motor-driven mechanism between a stored position and a plurality of elevated positions, the device comprising a base having two opposite ends and two opposite sides, a first elongated vertically-extending post member mounted by its lower end on the base, a second elongated vertically extending post member of substantially the same height as the first post member, a first elongated parallelogram linkage extending between the side base sides and connecting the upper end of the first post member to the lower end of the second post member for the second post member to be moved by the first linkage relative to the base parallel to the first post member, the second post member being skewed in shape transverse to the base sides between its bottom and top ends, a third vertically extending post member, a secondelongated parallelogram linkage extending generallyparallel to the first linkage in the opposite direction thereto and connecting the upper end of the second post member and the third post member for the third post member to be moved by the second linkage relative to the base parallel to the first and second post members, the second linkage being displaced transversely from the first linkage by the said skew of the second post member for the two linkages to be movable alongside each other in movement of the device to the said stored position, a first motor operatively connected between the first and second post members for moving the second post member relative to the first post member, and a second motor operatively connected between the second and third post members for moving the third post member relative to the second post member.

DESCRIPTION OF THE DRAWINGS A device which is a specific embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 is a general perspective view of the device showing the man-carrying platform thereof in an elevated position,

FIG..2 is a similar view to FIG. 1, but showing the platform in its lowermost stored position, and

FIG. 3 is a schematic diagram of the electrical/hydraulic circuit employed for the device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device comprises a base frame constituted by two parallel longitudinal beams 10, rigidly connected together by two parallel cross-beams 11, the transverse spacing between the two beams being such that the frame can be passed through a standard door opening of width 3 feet. The frame is provided at each of the ends of the beams 10 with a caster wheel 12 and a brace arm 13, which can be swung about a pivot 14 from the brace position illustrated to a stored position that is within the outline of the base frame. Each brace arm is provided at its outer end with a jack 15 engageable in known manner with the ground to stabilize the device while in use.

A rigid upright first post member 16 is mounted on one cross-beam 11, additional rigidity being provided by a cross-strut 17 extending between the post 16 and the other cross-brace 11. A first elongated linkage is constituted by two parallel arms 18 and 19, which are pivotally connected respectively at 20 and 21 to the upper end of the post 16. The arms are connected .at their other ends by respective pivots such as 22 (FIG. 1) to a second or intermediate post member 23. It will be seen that the upper part of the first post 16, the lower part of the second post 23, and the two parallel .arms 18 and 19 together form a first parallelogram linkfree end of the piston 26 is pivotally connected at 27 to the parallelogram arm 18.

The upper end of the second post has pivotally connected thereto, about respective pivots 28 and 29, a pair of parallel arms 30 and 31, which arein turnpivotally connected about respective pivots 32 and 33 to a thirdpost member 34, the parallel arms and the corresponding portions of the two posts 23 and 24 together forming a second parallelogram linkage. This second stage of the apparatus is elevated as required, in a similar manner to the first stage, and independently thereof, by means of a hydraulic motor operatively connected between the second and third post members. In this embodiment the motor is also constituted by a piston and cylinder unit, having the lower end of the cylinder 35 pivotally connected at 36 to the lower end of the second post, while the free end of the piston 36 is pivotally connected at 37 to the arm 30. A mancarrying platform 38 is rigidly fastened to the third post 34 and carries a control unit 39 by which operation of the device is controlled from the platform.

It will be seen from the drawings, particularly from FIG. 1, that the first post 16 is mounted to one side of the base framework, much nearer to one beam than to the other, and the first linkage extends parallel to and correspondingly more closely adjacent to the same beam 10, while remaining within the space bounded by a vertical projection of the outer perimeter of the base frame. The second post is of transverse cranked or skewed shape, whereby a plane containing the two arms 18 and 19 is transversely spaced from a corresponding parallel plane containing the two arms 30 and 31. The linkages can therefore move and lie freely alongside one another, as illustrated by FIG. 2, when they overlap as seen in side evelation. The two sets of arms extend in opposite directions, i.e., as considered from their secured ends to their movable ends, but are .in series with one another when considering the height-to which the wholedevice can elevatethe platform. The arms 30 and 31 are somewhat longer than the arms l8 and 19 so that in the stored position the platform is adjacent one end of the base frame and can easily be mounted by the operator. I am therefore able to provide a practical device of inexpensive construction wherein the two series-connected linkages lie alongside each other, within the projected area of the base frame, while in its stored position, and the device can therefore readily be passed through a regularsize doorway of a factory or plant, and yet when fully extended it can elevate a man to a height of at least about 50 feet, while remaining completely stable.

The device is moved from place to place on the caster wheels 12; upon stopping the brace arms 13 are swung fully out-and the jacks are operated to be in firm contact with the floor. The operator then climbs into the man-carrying platform '38 while it is at the position shown in FIG. 2, and by means of the control unit 39 can operate either of the hydraulic motors to elevate himself. By suitable selection of which of the two motors is operated the operator can also move the platform over a distance of approximately 10. feet parallel to the base-frame, while remaining at all times within or sufficiently close to the area of the base-frame to provide a safe stable operation.

Referring now especially to FIG. 3 the equipment associated with each motor is essentially similar, and will therefore be given the same reference, but with the suffix a for that associated with the first motor and with the suffix b for that associated with the second motor. Each hydraulic motor is supplied with hydraulic fluid from a reservoir 40 by means of a motor-driven pump, comprising pump 41 and electric motor 42. The liquid supplied by the pump passes through a first check valve 43 to flexible hose 44, and thence through another check valve 45 to the respective hydraulic cylinder 24 or 35. If at any time the pressure of the liquid supplied by the motor is excessive it is relieved by a valve 46 and returned to the reservoir. If at any time the motor 42 or the pump 41 fail to operate then the check valve 43 retains the liquid in the respective hydraulic motor, so that there is no sudden descent of the platform 38. Similarly, if there is any leakage in any of the hoses or their connections, then the check valve 45 will perform the same function. v

The liquid from the hydraulic motor is returned through an adjustable flow control valve 47, which permits the rate of descent of the platform to be controlled, the lowering being controlled by a solenoidoperated valve 48, that returns the liquid to the reservoir 46 via a clear plastic hose 49, permitting the operator to observe that liquid is flowing therein.

Each electric motor 42 is controlled by a motor solenoid 50 which solenoid is in turn controlled by the respective up-switch 51 in the control unit 39. The solenoid valves 48 are controlled by respective downswitches 52 in the unit 39. The unit is supplied with its operative power from a battery 53, which is provided with a conventional permanently connected battery charger 54. All of the operating mechanism comprising the battery, motors, pumps, etc., are contained in a simple enclosure 55 mounted on'the base frame, In some embodiments a duplicate control unit will be provided for remote control of the platform or, in embodiments which operate only as a hoist or crane without man-carrying capacity, then only a remote" control unit will be provided.

This separation of the operation of the two motors etc. also helps to ensure against sudden and total failure of the device, and it is usable for many functions with only one motor etc. operative.

The particular embodiment described above comprises two series-connected linkages extending in opposite directions to one another and storable alongside each other, but the invention comprises more than two such linkages with each successive linkage extending oppositely to the preceding linkage. in actual commercial practice, especially for a device intended for mancarrying operation, it is unlikely that more than four linkages would be required; with added linkages consideration must be given to having the brace arms extendable to much greater widths, to provide the necessary transverse stability. As with the above-described embodiment preferably a separate motor and associated operating mechanism is provided for each linkage, in view of marked advantages of such an arrangement.

I claim: 7

1. An elevating device including an elevatable part movable by a motor-driven mechanism between a stored position and a plurality of elevated positions, the device comprising a base, having two opposite ends and two opposite sides, a first elongated verticallyextending post member mounted by its lower end on the base, a second elongated vertically extending post member, a first swag ersaraieisgsn' linkage extending from the first post member toward one of the said base ends and connecting the upper end of the first post member to the lower end of the second post member for the second post member to be moved by the first linkage relative to the base and parallelto the first post member, the second post member being skewed in shape transverse to the base sides between its bottom and top ends, a third vertically extending post member I constituting the said elevatable part, a second elongated parallelogram linkage extending from the second post member toward the other of said base ends generally parallel to the first linkage and connecting the upper end of the second post member and the third post member for the third post member to be moved by the second linkage relative to the base and parallel to the first and second post members, the second linkage being disposed relative to the first linkage by the said skew of the second post member for the two linkages to be movable alongside each other in movement of the device to the said stored position and to lie alongside each other in the said stored position, a first motor operatively connected between the first and second post members for moving the second post member relative to the first post member, and a second motor operatively connected between the second and third post members for moving the third post member relative to the second post member.

2. The device claimed in claim 1, wherein each of said first and second motors comprise a hydraulic piston and cylinder motor unit supplied with operating fluid by an individual motor-driven pump.

3. The device claimed in claim 1, wherein the said first motor comprises a hydraulic piston and cylinder operatively connected between the base and the second post member for elevation of the latter upon supply of hydraulic fluid to the hydraulic motor cylinder, a connection between the said pump and hydraulic motor cylinder, a check valve in the said connection through which fluid passes from the pump into the hydraulic motor cylinder, means for controlling the hydraulic motor to elevate the device, a solenoid valve controlling the flow of fluid from the cylinder of the hydraulic motor, and means for controlling the solenoid valve to lower thedevice.

4. The device claimed in claim 1, wherein the said second motor comprises a hydraulic piston and cylinder operatively connected between the second and third post members for elevation of the latter upon supply of hydraulic fluid to the hydraulic motor cylinder, a motor-driven pump for supplying hydraulic fluid to the hydraulic motor cylinder, a connection between the said pump and hydraulic motor cylinder, a check valve in the said connection through which fluid passes from the pump into the hydraulic motor cylinder, means for controlling the hydraulic motor to elevate the device, a solenoid valve controlling the flow of fluid from the cylinder of the hydraulic motor, and means for controlling the solenoid valve to lower the device.

5. The device as claimed in claim 3, and comprising separate check valves disposed at opposite ends of the said connection between the pump and the hydraulic motor cylinder.

6. The device as claimed in claim 4, and comprising separate check valves disposed at opposite ends of the said connection between the pump and the hydraulic motor cylinder. 

1. An elevating device including an elevatable part movable by a motor-driven mechanism between a stored position and a plurality of elevated positions, the device comprising a base having two opposite ends and two opposite sides, a first elongated vertically-extending post member mounted by its lower end on the base, a second elongated vertically extending post member of substantially the same height as the first post member, a first elongated parallelogram linkage extending from the first post member toward one of the said base ends and connecting the upper end of the first post member to the lower end of the second post member for the second post member to be moved by the first linkage relative to the base and parallel to the first post member, the second post member being skewed in shape transverse to the base sides between its bottom and top ends, a third vertically extending post member constituting the said elevatable part, a second elongated parallelogram linkage extending from the second post member toward the other of said base ends generally parallel to the first linkage and connecting the upper end of the second post member and the third post member for the third post member to be moved by the second linkage relative to the base and parallel to the first and second post members, the second linkage being disposed relative to the first linkage by the said skew of the second post member for the two linkages to be movable alongside each other in movement of the device to the said stored position and to lie alongside each other in the said stored position, a first motor operatively connected between the first and second post members for moving the second post member relative to the first post member, and a second motor operatively connected between the second and third post members for moving the third post member relative to the second post member.
 2. The device claimed in claim 1, wherein each of said first and second motors comprise a hydraulic piston and cylinder motor unit supplied with operating fluid by an individual motor-driven pump.
 3. The device claimed in claim 1, wherein the said first motor comprises a hydraulic piston and cylinder operatively connected between the base and the second post member for elevation of the latter upon supply of hydraulic fluid to the hydraulic motor cylinder, a connection between the said pump and hydraulic motor cylinder, a check valve in the said connection through which fluid passes from the pump into the hydraulic motor cylinder, means for controlling the hydraulic motoR to elevate the device, a solenoid valve controlling the flow of fluid from the cylinder of the hydraulic motor, and means for controlling the solenoid valve to lower the device.
 4. The device claimed in claim 1, wherein the said second motor comprises a hydraulic piston and cylinder operatively connected between the second and third post members for elevation of the latter upon supply of hydraulic fluid to the hydraulic motor cylinder, a motor-driven pump for supplying hydraulic fluid to the hydraulic motor cylinder, a connection between the said pump and hydraulic motor cylinder, a check valve in the said connection through which fluid passes from the pump into the hydraulic motor cylinder, means for controlling the hydraulic motor to elevate the device, a solenoid valve controlling the flow of fluid from the cylinder of the hydraulic motor, and means for controlling the solenoid valve to lower the device.
 5. The device as claimed in claim 3, and comprising separate check valves disposed at opposite ends of the said connection between the pump and the hydraulic motor cylinder.
 6. The device as claimed in claim 4, and comprising separate check valves disposed at opposite ends of the said connection between the pump and the hydraulic motor cylinder. 